This invention relates to ventilator grills. A simple form of grill comprises a plate defining an array of apertures thrugh which air can pass. In a motor vehicle, it is desirable that the occupant be able to control the direction of the flow of air through the grill. There have been many proposals for devices for controlling the flow of air through a ventilator grill. For example, in one such device the grill includes a set of parallel louvres mounted in an aperture in a dashboard and coupled together in a gang so that the occupant can alter the angular orientation of the louvres relative to the aperture. This arrangement suffers from the disadvantage that the louvres are visible to the occupant and interrupt the contours of the dashboard.